Oxidation catalysts and process for preparing same

ABSTRACT

Novel compounds, particularly suitable as oxidation catalysts, are prepared using critical amounts of uranium, antimony and an element from Group IV B of the Periodic Table.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention is directed to novel compounds particularly suitable asoxidation catalysts containing critical amounts of uranium, antimony andan element from Group IV B of the Periodic Table and to a procedure forpreparing the same using critical amounts of said elements.

2. Description of the Prior Art

Oxidation catalysts consisting essentially of oxides of antimony anduranium are old and well known. Such catalysts and their uses aredescribed in U.S. Pat. Nos. 3,198,750 and 3,308,151 to Callahan andGertisser. Antimony-uranium oxide catalysts are used primarily forconverting propylene, in the presence of ammonia and a gas containingmolecular oxygen, to acrylonitrile. Other uses include the ammoxidationof isobutylene to methacrylonitrile and the oxidative conversions ofpropylene to acrolein, isobutylene to methacrolein, butene-1 or butene-2to 1,3-butadiene, and isoamylenes to isoprene. It has been shown byGrasselli and Callahan in the Journal of Catalysis, 14, 93-103 (1969)that the most effective catalysts are obtained when the antimony touranium atomic ratio is greater than three. Their best catalyst had anantimony to uranium atomic ratio of 4.6. The sole uranium containingphase detected in this catalyst was USb₃ O₁₀ according to Grasselli andSuresh, Journal of Catalysis, 25, 273-291 (1972). The excess antimonyoxide insured that undesirable uranium-containing phases, such as USbO₅and U₃ O₈ were not formed. U.S. Pat. No. 3,816,596 to Wise describes amethod of making a catalyst consisting essentially of USb₃ O₁₀.Antimony-uranium oxide catalysts may be made attrition resistant byadding silica as described in U.S. Pat. No. 3,341,471 to Callahan et al.

Attempts have been made to improve the antimony-uranium oxide catalystby combining the optimum antimony-uranium oxide composition with theoxides of most of the metallic elements of the Periodic Table. See, forexample, U.S. Pat. Nos. 3,328,315 and 3,431,292 to Callahan et al andBritish Pat. No. 1,007,929 to Distiller's Company Limited. Based onstarting materials, every catalyst tested in these patents had anantimony to uranium atomic ratio of 4.0 to 4.6, i.e. close to theoptimum composition of Grasselli and Callahan.

SUMMARY OF THE INVENTION

We have found that if we heat for a sufficient length of time at atemperature of at least about 850° C. an intimate mixture containing (1)the oxides of uranium, antimony and an element from Group IV B of thePeriodic Table (titanium, zirconium or hafnium) or (2) compounds of saidelements that will decompose or will otherwise be converted to saidoxides at said temperature, wherein the atomic ratios of said elementsare within selected critical ranges, preferably in molecular oxygen,such as air, we obtain a compound, believed to be crystalline, in whichsaid elements and oxygen are chemically combined within selectedcritical atomic ratios, which compound is more highly active as anoxidation catalyst than the prior art catalysts referred to above andwhich exhibits excellent selectivity in the production of acrylonitrilefrom propylene.

Examples of oxides that can be heated as part of the mixture describedabove include UO₂, U₃ O₈, UO₃, Sb₂ O₃, Sb₂ O₄, Sb₂ O₅, Ti₂ O₃, TiO₂,ZrO₂, HfO₂, UTiO₅, USbO₅, USb₃ O₁₀, etc. Examples of compounds that willbe converted to these oxides upon heating include UO₂ (NO₃)₂.6H₂ O, UO₂C₂ O₄.3H₂ O, UO₂ (C₂ H₃ O₂)₂.2H₂ O, Sb₂ (C₄ H₄ O₆)₃.6H₂ O, Sb(C₂ H₃O₂)₃, (NH₄)₂ TiO(C₂ O₄)₂. H₂ O, Ti₂ (C₂ O₄)₃.10H₂ O, Zr(C₂ H₃ O₂)₄,ZrO(C₂ H₃ O₂)₂, and any hydrated oxide or hydroxide of antimony,uranium, titanium, zirconium or hafnium.

Intimate mixing of the above materials greatly facilitates the formationof the desired crystalline phase. In a preferred embodiment of ourinvention, intimate mixing is achieved, for example, by co-precipitationof the hydroxides or hydrated oxides from acidic solution by adding asuitable base, such as ammonium hydroxide. The precipitate so obtainedis washed with water, dried at a temperature of 100°-200° C. for fromabout 2 to about 24 hours and then calcined. The acidic solution isconveniently prepared using various soluble salts as starting materials.These include UO₂ (NO₃)₂.6H₂ O, UO₂ (C₂ H₃ O₂)₂.2H₂ O, UCl₃, UCl₄, UF₆,UBr₄, SbCl₃, Sb(C₂ H₃ O₂)₃, SbF₃, SbCl₅, Ti₂ (C₂ O₄)₃.10H₂ O, ZrOCl₂.8H₂O, ZrO(C₂ H₃ O₂)₂, and ZrOBr₂.XH₂ O. Alternatively, one can prepareacidic solutions from the metals themselves or their oxides. Forexample, Sb metal can be reacted with concentrated nitric acid to obtainthe hydrous oxide, which can then be dissolved in concentratedhydrochloric acid.

The amounts of the reactant components used in the preparation of thecatalyst herein are critical. Thus the metals in the reactant componentsmust be present in amounts such that the atomic ratio of antimony touranium is at least about 1.35:1, preferably at least about 1.50:1, butno higher than about 2.75:1, preferably no higher than about 2.5:1; theatomic ratio of the Group IV B element to uranium is at least about0.25:1, preferably at least about 0.5:1, but no higher than about1.65:1, preferably no higher than about 1.5:1. In addition the atomicratios of the sum of the antimony and the Group IV B element to uraniummust be within a range of about 3.5:1 to about 2.5:1, preferably about3.3:1 to about 2.8:1, with the most preferred ratio being about 3:1. Wehave found that such reactant amounts are critical if we are to obtainthe new chemical compounds herein having the critical amounts ofuranium, antimony, Group IV B element and oxygen, namely a crystallinecompound falling within the following formula:

    USb.sub.3-x A.sub.x O.sub.9-10,

wherein A is a Group IV B element, namely, titanium, zirconium orhafnium, x is the number about 0.25 or higher, preferably about 0.5 orhigher, but no higher than about 1.50, preferably no higher than about1.25. If amounts outside the defined reactant amounts are used in theattempted preparation of the new compound, the new compound definedabove is either not obtained or if it is obtained appreciable amounts ofother undesirable compounds containing one or more of the elementspresent in the reaction mixture, such as TiO₂, UTiO₅, USbO₅, USb₃ O₁₀,U₃ O₈, Sb₂ O₄, Sb₂ O₅, ZrO₂, HfO₂, etc., are also obtained. Compoundsthat can form in addition to the novel compounds when the criticalamounts of reactant components are not used cannot easily be separatedfrom the novel compounds. The resultant mixture will have a relativelylow activity or poorer selectivity or both.

Once the critical amounts of reactant components are selected, thereaction mixture containing the same must be heated (calcined) to acritical temperature of at least about 850° C., preferably at leastabout 875° C., preferably in an atmosphere containing molecular oxygen,in order to obtain the defined novel compound. Although the temperaturecan be as high as about 1050° C., or even higher, in general atemperature of about 1000° C. need not be exceeded. Once having selecteda critical temperature within the above range, the mixture is maintainedat such temperature for a time sufficient to crystallize the newcompounds herein. At the lower temperatures, longer calcination periodsare required, while at the higher temperatures lower periods willsuffice. Thus, the time required for calcination can be as low as about15 minutes, generally at least about 1 hour, but a period of no morethan about 24 hours, generally no more than about 18 hours, willsuffice. The heating is carried out at atmospheric pressure, althoughelevated pressures can be used if desired.

The catalyst obtained herein can be employed as an oxidation catalystusing conventional procedures. Thus, in the conversion of propylene toacrylonitrile, in the presence of ammonia and a gas containing molecularoxygen, such as air or oxygen itself, a gaseous mixture containing suchreactants is brought into contact with the novel catalyst compounddefined herein at a pressure of about 0 to about 100 pounds per squareinch gauge (about 0 to about 7.0 kilograms per square centimeter),preferably about 0 to about 50 pounds per square inch gauge (about 0 toabout 3.5 kilograms per square centimeter), in a temperature range ofabout 375° to about 525° C., preferably about 450° to about 495° C., ata contact time of at least about 0.01 second, preferably in the range ofabout 0.1 to about 15 seconds. The molar ratio of oxygen to propylene isabout 0.5:1 to about 5:1, preferably about 1:1 to about 2:1, while themolar ratio of ammonia to propylene is greater than about 0.9:1 butpreferably no greater than about 1.5:1. By contact time we mean the bulkvolume of the catalyst in cubic centimeters divided by the flow rate ofthe total reactants in vapor form at reaction conditions in cubiccentimeters per second. The novel catalyst herein can be used in afixed-bed or a fluidized-bed reactor.

DESCRIPTION OF PREFERRED EMBODIMENTS

The following will provide a further understanding of the inventionclaimed herein.

EXAMPLE I

To a flask equipped with a mechanical stirrer and containing 80.3 gramsof Sb₂ O₃ there was added 321 ml. of concentrated nitric acid and themixture was refluxed for one-half hour. Meanwhile a solution of 60.2grams of UO₂ (NO₃)₂.6H₂ O in 100 ml. of hot distilled water wasprepared. The latter solution was then added to the flask and refluxingwas continued for another three hours. The mixture was then brought to apH of 8.0 by the addition thereto of concentrated ammonium hydroxide.The resulting precipitate was recovered by filtration, dried in an ovenfor 16 hours at a temperature of 120° C. and then calcined in air at atemperature of 900° C. for 16 hours. The product by X-ray diffractionwas found not to be a single phase but contained the followingcrystalline compounds: USb₃ O₁₀ and Sb₂ O₄.

EXAMPLE II

To a solution containing 100 cc. of water and 6.84 grams of SbCl₃ therewas first added 40 cc. of concentrated HCl and then a solutioncontaining 100 cc. of water and 5.02 grams of UO₂ (NO₃)₂.6H₂ O. Thehydrous metal oxides were precipitated from solution by the additionthereto of 120 cc. of concentrated ammonium hydroxide. The precipitateobtained was filtered, washed with 1 liter of water and then placed in adrying oven for about 16 hours at a temperature of 120° C. The driedprecipitate was then calcined in air at a temperature of 910° C. for 16hours. In this example, as well as in those following, the preparationwas carried out at atmospheric pressure and, unless otherwise stated, atatmospheric temperature. The product obtained, amounting to 7.05 grams,was shown by X-ray diffraction patterns to be the crystalline chemicalcompound USb₃ O₁₀, with only small amounts (less than about 10 weightpercent, based on the total compounds produced) of Sb₂ O₄ and USbO₅.

EXAMPLE III

To a solution containing 100 cc. of water there was first added 5.48grams of SbCl₃ and 5.02 grams of UO₂ (NO₃)₂.6H₂ O, followed by 40 cc. ofconcentrated HCl and then a solution containing 1.62 grams of Ti₂ (C₂O₄)₃.10H₂ O and 100 cc. of water. The hydrous metal oxides wereprecipitated from solution by the addition thereto of 120 cc. ofconcentrated ammonium hydroxide. The precipitate obtained was filtered,washed with 1 liter of water and then placed in a drying oven for about16 hours at a temperature of 120° C. The dried precipitate was thencalcined in air at a temperature of 910° C. for 16 hours. The productobtained, amounting to 6.70 grams, was shown by X-ray diffractionpatterns, to be the crystalline chemical compound USb₂.4 Ti₀.6 O₉₋₁₀.The compound obtained in this example falls within the definition of thecompounds defined and claimed herein.

EXAMPLE IV

The procedure of Example II was repeated, except that 4.56 grams ofSbCl₃ and 2.7 grams of Ti₂ (C₂ O₄)₃.10H₂ O was used. The singlecrystalline compound USb₂.0 Ti₁.0 O₉₋₁₀ was obtained. The compoundobtained herein also falls within the definition of the compoundsdefined and claimed herein.

EXAMPLE V

This time the procedure of Example II was repeated using 6.84 grams ofSbCl₃, 10.04 grams of UO₂ (NO₃)₂ 0.6H₂ O and 8.10 grams of Ti₂ (C₂O₄)₃.10H₂ O. A compound of the type USb_(3-x) Ti_(x) O₉₋, wherein x is anumber between 1.0 and 1.2 was obtained, along with a small amount ofTiO₂. Again, the predominant compound obtained herein falls within thedefinition of the compounds defined and claimed herein.

EXAMPLE VI

In this example, the run of Example IV was repeated, except that 4.56grams of SbCl₃ and 10.86 grams of Ti₂ (C₂ O₄)₃.10H₂ O were used. Theproduct obtained did not consist substantially of a single phase, butcontained the same compounds as in Example V, except that the amount ofTiO₂ was greater.

EXAMPLE VII

The procedure of Example V was followed, except that 13.5 grams of Ti₂(C₂ O₄)₃.10H₂ O and 2.28 grams of SbCl₃ were used. In addition to thecompounds found in Example V, the product also contained significantamounts of UTiO₅.

EXAMPLE VIII

The procedure of Example V was repeated except that no antimony compoundwas present and 10.04 grams of UO₂ (NO₃)₂.6H₂ O and 16.20 grams of Ti₂(C₂ O₄)₃.10H₂ O were used. The product obtained was a mixture consistingof substantial amounts of UTiO₅ and TiO₂.

EXAMPLE IX

To a solution containing 9.12 grams of SbCl₃, and 5.02 grams of UO₂(NO₃)₂.6H₂ O and 100 cc. of water there was 40 cc. of concentrated HCland then a solution containing 2.43 grams of Ti₂ (C₂ O₄)₃.10H₂ O and 100cc. of water. The hydrous metallic oxides were precipitated by theaddition to the resulting solution of 120 cc. of concentrated ammoniumhydroxide. The precipitate was filtered, washed with 1 liter of water,dried in an oven for about 16 hours at a temperature of 120° C. and thencalcined in air at a temperature of 910° C. for 16 hours. The product byX-ray diffraction was found not to be a single phase but containedsubstantial amounts of Sb₂ O₅ and USb₃ O₁₀ and a lesser amount of TiO₂.

EXAMPLE X

Antimony powder (12.18 grams) was added to 61 grams of concentratednitric acid at 95° C. over a period of 15 minutes, the mixture wasboiled for 5 minutes, diluted with 50 grams of distilled water andfiltered. The filter cake was washed once with 10 grams of distilledwater then added to 7.01 grams of U₃ O₈, 5.10 grams of nitric acid and14.4 grams of distilled water. The mixture was stirred at roomtemperature and an aqueous ammonia solution having a specific gravity of0.880 was added dropwise thereto until the pH reached 6.5. The resultingsuspension was filtered and the precipitate was washed twice byresuspension for 15 minutes in 50 grams of distilled water containing0.025 gram of carboxymethyl cellulose. The washed filter cake wassuspended in 1000 grams of distilled water and a solution containing3.41 grams of tetranormalpropylene orthotitanate [(CH₃ CH₂ CH₂)₄ TiO₄ ]in 87.9 grams of benzene was added dropwise. The suspension was stirredfor one hour, filtered and the precipitate washed once by resuspensionin 100 grams of water. The filter cake was dried at 110° C. for 15 hoursand sieved to pass 30 mesh, mixed with 0.37 gram of graphite and thenpelleted. The pellets were heated in air from 300° to 800° C. at therate of 21° C. per hour and held at a temperature of 800° C. for 16hours. The product by X-ray diffraction was found not to be a singlephase but contained the following crystalline compounds: Sb₂ O₅, USb₃O₁₀, USbO₅ and smaller amounts of TiO₂ and Sb₂ O₄.

EXAMPLE XI

To 1 liter of water there was added 91.24 grams of SbCl₃ and then 400cc. of concentrated HCl. To this solution there was added a solutioncontaining 100 cc. of water and 100.46 grams of UO₂ (NO₃)₂ 0.6H₂ O andthen a solution containing one liter of water and 64.44 grams ofZrOCl₂.8H₂ O. To obtain the corresponding metal oxide precipitates,there was added to the resulting solution 1200 cc. of concentratedammonium hydroxide. The precipitate obtained was washed with 10 litersof water and then placed in a drying oven for about 16 hours at atemperature of 120° C. The dried precipitate was then calcined in air ata temperature of 910° C. for 16 hours. The product obtained was found byX-ray diffraction to be the crystalline chemical compound USb₂ ZrO₉₋₁₀.The compound obtained in this example falls within the definition of thecompounds defined and claimed herein.

EXAMPLE XII

To a solution containing one liter of water and 104.9 grams of SbCl₃there was added 400 cc. of concentrated HCl, a solution containing 1liter of water and 50.21 grams of U0₂ (NO₃)₂.6H₂ O and then a solutioncontaining 400 cc. of water and 32.23 grams of ZrOCl₂.8H₂ O. The metaloxides were precipitated by the addition to the resulting solution of1200 cc. of concentrated ammonium hydroxide. The precipitate wasfiltered, washed with 4 liters of water, dried in an oven for about 16hours at a temperature of 120° C. and then calcined in air at atemperature of 910° C. for 16 hours. The product by X-ray diffractionwas found not to be a single phase but contained substantial amounts ofSb₂ O₅ and USb_(3-x) Zr_(x) O₁₀, wherein x is a number between 0.25 and1.0.

Each of the above catalysts was used to prepare acrylonitrile asfollows. A 0.5 ml. sample of 20-40 mesh catalyst was weighed and chargedto a 0.64 cm. O.D. × 0.48 cm. I.D. tubular stainless-steel microreactor.The reactor was placed in an electric furnace. Air was flowed over thecatalyst at the rate of 32.5 cc-STP min⁻ ¹ as the furnace was heated toabout 450° C. When the furnace temperature reached 450° C., the reactionwas carried out in cyclic fashion. The ammonia and propylene flows werestarted at 3.0 and 2.5 cc-STP min⁻ ¹ , respectively. The furnacetemperature was adjusted so that the reaction temperature, as measuredby a sheathed thermocouple located within the catalyst bed, was 475° C.After 15 minutes on-stream, the product stream was sampled and thenanalyzed by gas chromatography. After another 15 minutes on-stream, thepropylene and ammonia flows were shut off. The catalyst was regeneratedby allowing the air flow to continue for 30 minutes. Propylene andammonia flows were then resumed to begin the next on-stream period. Thisprocedure was repeated for 5 or 6 cycles.

Thus propylene, air and ammonia were reacted at atmospheric pressure ina 1.0:13:1.2 molar ratio at a contact time of 0.28 to 0.29 second.

Average values are reported in Table I for percent conversion, percentselectivity, present yield, and relative activity. These are defined as:##EQU1## where x is the mole fraction of propylene converted.

                                      TABLE I                                     __________________________________________________________________________                                   Percent                                        Catalyst           Grams                                                                              Mol Percent                                                                          Selectivity                                    From       Stoichiometry                                                                         of   Propylene                                                                            To      Acrylonitrile                                                                         Relative                       Run No.                                                                             Example                                                                            U Sb                                                                              Ti                                                                              Zr                                                                              Catalyst                                                                           Converted                                                                            Acrylonitrile                                                                         Yield   Activity                       __________________________________________________________________________    1     I    1.0                                                                             4.6                                                                             0 0 0.431                                                                              16.0   82.1    13.1    1.1                            2     II   1.0                                                                             3.0                                                                             0 0 0.495                                                                              16.3   80.3    13.1    1.0                            3     III  1.0                                                                             2.4                                                                             0.6                                                                             0 0.638                                                                              61.3   90.6    55.5    4.1                            4     IV   1.0                                                                             2.0                                                                             1.0                                                                             0 0.838                                                                              88.7   89.0    78.9    7.2                            5     V    1.0                                                                             1.5                                                                             1.5                                                                             0 0.466                                                                              92.8   77.4    71.8    15.7                           6     VI   1.0                                                                             1.0                                                                             2.0                                                                             0 0.710                                                                              50.8   46.3    23.5    2.8                            7     VII  1.0                                                                             0.5                                                                             2.5                                                                             0 0.678                                                                              25.3   26.7     6.8    1.2                            8     VIII 1.0                                                                             0 3.0                                                                             0 0.570                                                                              17.5   27.2     4.8    0.9                            9     IX   1.0                                                                             4.0                                                                             0.9                                                                             0 0.563                                                                              33.7   58.4    19.7    2.0                            10    X    1.0                                                                             4.0                                                                             0.9                                                                             0 0.656                                                                              45.7   84.5    38.6    2.6                            11    XI   1.0                                                                             2.0                                                                             0 1.0                                                                             0.652                                                                              92.8   79.4    73.7    11.2                           12    XII  1.0                                                                             4.6                                                                             0 1.0                                                                             0.585                                                                              32.2   82.6    26.6    1.5                            __________________________________________________________________________

The data in Table I amply emphasize the uniqueness of the novelcomposition defined and claimed herein. Note that when the novelcomposition of Examples III, IV, V and XI, were used in Runs. Nos. 3, 4,5 and 11, respectively, to convert propylene, air and ammonia toacrylonitrile exceedingly high yields were obtained within theexceedingly short period of 0.3 second. The remaining catalysts, whichdid not fall within the scope of the novel catalysts herein, resulted inexceedingly poor yields of acrylonitrile when used in the same process.

An additional series of runs was carried out, this time using thecatalyst prepared in Example IV to show the effect of temperature of thenovel catalysts herein in the ammoxidation reaction defined above. Inall of the runs summarized below in Table II except Run No. 18, themolar ratio of propylene to air to ammonia was 1.0:11.0:1.1; in thelatter run the corresponding ratio was 1.0:10.0:1.0.

                                      TABLE II                                    __________________________________________________________________________    Run No.      13   14   15   16   17   18   19   20                            __________________________________________________________________________    Temperature, ° C.                                                                   401  426  455  475  475  475  486  495                           Contact Time, Seconds                                                                      0.73 0.71 0.68 0.41 0.65 0.72 0.40 0.40                          Mol Percent Propylene                                                         Converted    34.9 70.4 87.7 93.1 97.6 98.9 97.0 97.9                          Selectivity To                                                                Acrylonitrile                                                                              78.6 83.8 86.9 87.7 86.5 84.1 87.8 83.0                          Acrylonitrile Yield                                                                        27.5 59.0 76.4 81.7 84.4 83.2 85.2 81.2                          __________________________________________________________________________

The data in the above table show that the novel catalyst is effectiveover a wide temperature range. Although yields were somewhat low in RunNo. 13 this is due to the relatively low conversions of propylene. Anincrease in contact time would result in higher propylene conversion andaccordingly increased acrylonitrile yield. In general, however, while arelatively low temperature, as low as 401° C., or even less, it can beseen that best results are obtained when the novel catalysts herein areused in the ammoxidation reaction in a temperature range of about 450°to about 495° C.

An additional series of runs was made, using catalysts containingvarying amounts of uranium, antimony and zirconium, in the preparationof acrylonitrile from propylene, air and ammonia. The catalysts wereprepared by first dissolving UO₂ (NO₃)₂.6H₂ O, SbCl₃ and ZrO(C₂ H₃ O₂)₂in hydrochloric acid. To this solution there was then added ammoniumhydroxide until the pH thereof reached 8.0, at which point precipitatesof the hydrous metallic oxides were obtained. The precipitate wasrecovered by filtration, washed twice with water, dried overnight at120° C. and then calcined at 910° C. for 16 hours. The product obtainedin each was used to convert propylene, air and ammonia to acrylonitrilefollowing the procedure of Runs Nos. 1 to 12. The data obtained aresummarized below in Table III.

                                      TABLE III                                   __________________________________________________________________________    Stoichiometry                  Percent                                        Based On               Mol Percent                                                                           Selectivity                                    Starting Materials                                                                             Grams Of                                                                            Propylene                                                                             To      Acrylonitrile                                                                         Relative                       Run No.                                                                             U  Sb  Zr  Catalyst                                                                            Converted                                                                             Acrylonitrile                                                                         Yield   Activity                       __________________________________________________________________________    21    1.0                                                                              2.0 1.50                                                                              0.922 49.6    82.9    41.1    2.1                            22    1.0                                                                              2.5 0.75                                                                              0.418 61.0    87.8    53.6    6.3                            23    1.0                                                                              3.0 2.24                                                                              0.954 42.9    86.4    37.1    1.6                            24    1.0                                                                              0   4.50                                                                              1.085 19.6     7.8     1.5    0.6                            25    1.0                                                                              5.0 0.75                                                                              0.532 19.5    89.1    17.4    1.1                            26    1.0                                                                              2.0 1.00                                                                              0.496 82.0    83.5    68.4    9.6                            27    1.0                                                                              2.5 0.5 0.472 69.7    88.6    61.8    7.0                            28    1.0                                                                              1.5 1.5 0.666 87.7    74.2    65.1    8.9                            __________________________________________________________________________

The above data further show in Runs Nos. 22, 26, 27 and 28 that when thenovel catalyst herein is used to convert propylene to acrylonitrile, thenovel catalyst possesses an excellent activity and excellentacrylonitrile yields are obtained.

The novel catalyst of this invention can be combined with a binder orsupport, such as silica, in any conventional manner to make the catalystattrition resistant so that it can be used in a fluidized bed reactor.The preparation and use of such catalyst is exemplified by the followingrun.

Run No. 29

One liter of concentrated hydrochloric acid was added to a solutioncontaining 114.05 grams of SbCl₃ and 125.53 grams of UO₂ (NO₃).6H₂ O. Tothis solution there was added a solution containing 100.54 grams oftitanium sulfate and 2500 cc. of water. When 3 liters of concentratedammonium hydroxide was added to the resulting solution a yellowprecipitate was formed. The precipitate was recovered by filtration andthen washed with 25 liters of water. The filter cake, amounting to 24.8weight percent solids, was combined with 549.33 grams of LUDOX AS (anammonia-stabilized silica sol made and sold by du Pont, Wilmington,Del.). To make a 10 weight percent solids solution 1942 grams of waterwas added to the mixture of filter cake and LUDOX AS. The resultantmixture was sieved through a 30-mesh screen and spray dried. The bottomsand overhead were then mixed and oven dried overnight and then calcinedat 910° C. for 16 hours to obtain a product containing 50 weight percentUSb₂ TiO₁₀ and 50 weight percent SiO₂. A small portion of this catalyst,amounting to about 2 grams, was pressed into a pellet and subsequentlycrushed and sieved to obtain 20 to 40 mesh particles for testing in a 1cc. fixed bed microreactor. One milliliter of this catalyst, amountingto 0.696 gram, was placed in the reactor and propylene was converted toacrylonitrile as in Runs Nos. 1 to 12 over a period of 0.57 second, witha propylene conversion of 80.7 percent, acrylonitrile selectivity of87.2 percent and acrylonitrile yield of 70.4 percent.

Although the novel catalyst herein has been shown to be very effectivein the ammoxidation of propylene to acrylonitrile, the catalyst can alsobe used advantageously in other ammoxidation reactions such as theammoxidation of isobutylene to methacrylonitrile, and in oxidationreactions, such as oxidation reactions converting propylene to acrolein,isobutylene to methacrolein, butene-1 or butene-2 to 1,3-butadiene, andisoamylenes to isoprene.

Obviously, many modifications and variations of the invention, ashereinabove set forth, can be made without departing from the spirit andscope thereof, and, therefore, only such limitations should be imposedas are indicated in the appended claims.

We claim:
 1. The novel compound defined by the formula:

    USb.sub.3-x A.sub.x O.sub.9-10,

wherein A is a Group IV B element, x is the number about 0.25 to about1.50.
 2. The compound of claim 1 wherein the Group IV B element istitanium.
 3. The compound of claim 1 wherein the Group IV B element iszirconium.
 4. The compound of claim 1 wherein the Group IV B element ishafnium.
 5. The compound of claim 1 wherein x is the number about 0.5 toabout 1.25.
 6. A process for preparing a compound containing uranium,antimony, a Group IV B element and oxygen which comprises heating amixture containing (1) oxides of uranium, antimony and an element fromGroup IV B of the Periodic Table or (2) compounds of said elements thatwill decompose or be converted to said oxides during said heating,wherein the atomic ratio of antimony to uranium is about 1.35:1 to about2.75:1, the atomic ratio of the Group IV B element to uranium is about0.25:1 to about 1.65:1 and the atomic ratio of the sum of antimony andGroup IV B element to uranium is about 3.5:1 to about 2.5:1, at atemperature of at least about 850° C. for about 15 minutes to about 24hours.
 7. The process of claim 6 wherein the atomic ratio of antimony touranium is about 1.5:1 to about 2.5:1, the atomic ratio of the Group IVB element to uranium is about 0.5:1 to about 1.5:1 and the atomic ratioof the sum of antimony and the Group IV B element to uranium is about2.8:1 to about 3.3:1.
 8. The process of claim 6 wherein the atomic ratioof the sum of antimony and the Group IV B element to uranium is about3:1.
 9. The process of claim 6 wherein the temperature is about 875° toabout 1000° C. and the time is about 1 to about 18 hours.
 10. Theprocess of claim 6 wherein the Group IV B element is titanium.
 11. Theprocess of claim 6 wherein the Group IV B element is zirconium.
 12. Theprocess of claim 6 wherein the Group IV B element is hafnium.